Gents might use this upper-class bow (1-4)
I believe the answer is:
u-bend
'gents might use' is the definition.
I know nothing about this answer so I can't judge whether this works.
'upper-class bow' is the wordplay.
I cannot quite see how this works, but
'bow' could be 'bend' (both can mean a curve) and 'bend' is located in the answer.
'upper-class' could be 'u' (similar in meaning) and 'u' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'this' acts as a link.
Can you help me to learn more?
(Other definitions for u-bend that I've seen before include "Waste pipe kink" , "Waste pipe feature" , "Trap section of waste pipe" , "Air-trap in a pipe" , "Waste pipe gas trap" .)